1. Field of Invention
The subject of the invention is an insulating glazing unit and its manufacturing process.
2. Description of Related Art
One well-known type of insulating glazing unit comprises two glass sheets which are spaced apart by a cavity filled with gas, such as air, and which are kept apart and joined together by means of a spacer frame consisting of hollow metal strips folded over or assembled by corner pieces. The strips are provided with a molecular sieve whose function is especially to absorb the water molecules that are trapped during manufacture of the glazing unit in the intermediate air cavity and that would be liable to condense in cold weather, which causes the appearance of fogging.
To ensure that the glazing unit is sealed, the spacer frame is adhesively bonded to the glass sheets by an elastomer bead of the butyl rubber type, applied directly to the strips by extrusion through a nozzle. Each corner of the spacer frame is also provided at a corner piece with butyl rubber. Once the glazing has been assembled, the elastomer sealing bead has a function of temporarily providing mechanical retention of the glass sheets. Finally, a crosslinkable sealing mastic, of the polysulfide or polyurethane type, is injected into the peripheral groove bounded by the two glass sheets and the spacer frame, thereby completing the mechanical assembly of the glass sheets. The main function of the butyl rubber is to seal the inside of the glazing unit with respect to water vapor, whereas the mastic seals against liquid water and solvents.
The manufacture of this glazing unit requires several different materials, including the strips, the corner pieces, the molecular sieve and the organic seals, these materials not being assembled in one and the same operation.